/**
*      author: Y_Yao
*      created: 2025-01-18 20:02:15
**/

#include<bits/stdc++.h>

#define int LL
using namespace std;
using LL = long long;
const LL LLINF = 1e18;
const int INF = 0x3f3f3f3f;
int x;

void solve()
{
    cin >> x;
    int cnt = 1;
    int i = 1;
    while(cnt < x)
    {
        cnt *= i;
        i++;
    }

    cout << i-1 << endl;
}

signed main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);

    int t = 1;
    //cin >> t;
    while(t--)
    {
        solve();
    }
    return 0;
}